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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 72 of 326

This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1421

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents with a painful clunking sensation in her knee when extending from a flexed position. She underwent a posterior-stabilized total knee arthroplasty 18 months ago. Examination reveals a palpable catch at approximately 40 degrees of flexion. Which of the following is the underlying pathophysiology of this condition?

. Impingement of the anterior tibial post against the intercondylar notch
. Formation of a fibrous nodule at the superior pole of the patella catching in the intercondylar box
. Asymmetric wear of the polyethylene insert causing subluxation
. Oversizing of the patellar component leading to lateral tracking
. Rupture of the patellar tendon

Correct Answer & Explanation

. Impingement of the anterior tibial post against the intercondylar notch

Explanation

Patellar clunk syndrome occurs in posterior-stabilized TKA designs when a fibrous nodule forms at the superior pole of the patella. This nodule catches in the intercondylar box of the femoral component during extension from a flexed position.

Question 1422

Topic: 3. Adult Reconstruction (Hip & Knee)

In a patient undergoing revision total hip arthroplasty, the surgeon encounters severe pelvic discontinuity. Radiographs and intraoperative findings show complete separation of the superior and inferior hemipelvis. Which of the following surgical constructs is generally considered the most reliable for achieving stability and long-term fixation in this scenario?

. A jumbo hemispherical cup with multiple screws
. An isolated impaction bone grafting technique
. A cup-cage construct or custom triflange acetabular component
. A bipolar hemiarthroplasty articulating directly on native bone
. A standard cementless cup with a porous coating

Correct Answer & Explanation

. A jumbo hemispherical cup with multiple screws

Explanation

Pelvic discontinuity requires rigid stabilization between the superior and inferior halves of the pelvis. A cup-cage construct or a custom triflange component bridges the defect and provides mechanical stability to allow for potential biologic fixation or bridging bone formation.

Question 1423

Topic: 3. Adult Reconstruction (Hip & Knee)

When balancing a severe varus deformity during a primary total knee arthroplasty, the surgeon performs a sequential medial release. After releasing the deep medial collateral ligament (MCL) and removing osteophytes, the knee remains tight medially in extension but balanced in flexion. Which structure should be released next to correct the medial tightness in extension?

. Pes anserinus tendons
. Posteromedial capsule and semimembranosus
. Superficial medial collateral ligament
. Anterior cruciate ligament
. Lateral collateral ligament

Correct Answer & Explanation

. Pes anserinus tendons

Explanation

The posteromedial corner (posteromedial capsule and semimembranosus insertions) primarily affects the extension gap. Releasing these structures will correct medial tightness in extension without significantly affecting the flexion gap.

Question 1424

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male presents with acute onset of severe left knee pain 14 days after a primary total knee arthroplasty. The knee is swollen, erythematous, and warm. Aspiration yields purulent synovial fluid with a white blood cell count of 65,000 cells/uL (95% neutrophils). What is the most appropriate surgical management?

. Prescribe oral antibiotics and observe for 2 weeks
. Debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange
. One-stage revision arthroplasty
. Two-stage revision arthroplasty with an antibiotic spacer
. Arthrodesis of the knee

Correct Answer & Explanation

. Prescribe oral antibiotics and observe for 2 weeks

Explanation

For acute periprosthetic joint infections occurring within 4 weeks of the index procedure and involving a well-fixed implant, Debridement, Antibiotics, and Implant Retention (DAIR) with a modular component exchange is the standard of care.

Question 1425

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient with a metal-on-metal total hip arthroplasty presents 5 years postoperatively with groin pain and a palpable mass. MRI with metal artifact reduction sequence (MARS) reveals a large cystic lesion adjacent to the joint. Histology from a subsequent revision surgery shows a perivascular lymphocytic infiltrate. This reaction is best classified as which type of hypersensitivity?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type IV

Explanation

Aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) or adverse local tissue reactions (ALTR) in metal-on-metal hips are characterized by a perivascular lymphocytic infiltrate. This represents a Type IV (delayed, cell-mediated) hypersensitivity reaction to metal ions.

Question 1426

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty, optimizing patellofemoral tracking is crucial. Which of the following technical errors most strongly predisposes the patella to track laterally and potentially subluxate or dislocate?

. External rotation of the tibial component
. External rotation of the femoral component
. Internal rotation of the femoral component
. Medialization of the patellar component
. Excessive valgus alignment of the tibial resection

Correct Answer & Explanation

. External rotation of the tibial component

Explanation

Internal rotation of the femoral component medializes the trochlear groove relative to the extensor mechanism, significantly increasing the Q-angle and predisposing the patella to lateral tracking and subluxation.

Question 1427

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old active female undergoes a total hip arthroplasty via a posterior approach for a displaced femoral neck fracture. Compared to a bipolar hemiarthroplasty for the same indication, which of the following outcomes is most associated with total hip arthroplasty?

. Lower rate of postoperative dislocation
. Higher rate of long-term reoperation
. Better functional outcomes and lower reoperation rate
. Shorter operative time
. Decreased incidence of deep vein thrombosis

Correct Answer & Explanation

. Lower rate of postoperative dislocation

Explanation

In active elderly patients with displaced femoral neck fractures, THA provides better functional scores and lower long-term reoperation rates compared to hemiarthroplasty. However, THA is associated with a higher initial dislocation rate.

Question 1428

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is considered an absolute contraindication for a medial unicompartmental knee arthroplasty (UKA)?

. Age greater than 60 years
. Body mass index (BMI) of 32 kg/m2
. Inflammatory arthropathy
. Patellofemoral chondromalacia without bone-on-bone changes
. Intact anterior cruciate ligament

Correct Answer & Explanation

. Age greater than 60 years

Explanation

Inflammatory arthropathies (e.g., Rheumatoid arthritis) are absolute contraindications for unicompartmental knee arthroplasty due to the systemic, progressive nature of the joint destruction. Intact ACL is actually a prerequisite for UKA.

Question 1429

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon encounters a well-fixed, proximally porous-coated femoral stem that must be removed for a recurrent periprosthetic joint infection. To facilitate extraction while minimizing catastrophic bone loss, the surgeon plans an extended trochanteric osteotomy (ETO). What is the optimal location and length for the osteotomy?

. Posteromedial aspect, extending 5 cm distal to the stem tip
. Anterolateral aspect, extending exactly to the tip of the stem
. Anterolateral aspect, preserving the posterior soft tissue hinge, extending just distal to the porous coating
. Direct lateral aspect, extending the entire length of the femur
. Medial aspect, detaching the iliopsoas tendon

Correct Answer & Explanation

. Posteromedial aspect, extending 5 cm distal to the stem tip

Explanation

An extended trochanteric osteotomy (ETO) is typically performed on the anterolateral aspect of the femur, leaving the posterior structures (linea aspera and muscular attachments) intact as a hinge. It should extend just distal to the well-fixed portion (porous coating) to allow stem extraction.

Question 1430

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient with a large-diameter metal-on-polyethylene total hip arthroplasty presents with unexplained hip pain 4 years postoperatively. Radiographs show a well-fixed implant with a short, thin femoral trunnion. Serum cobalt levels are highly elevated, while chromium is normal. What is the most likely diagnosis?

. Polyethylene wear-induced osteolysis
. Mechanically assisted crevice corrosion (Trunnionosis)
. Aseptic loosening of the femoral stem
. Periprosthetic joint infection
. Iliopsoas impingement

Correct Answer & Explanation

. Polyethylene wear-induced osteolysis

Explanation

Trunnionosis is mechanically assisted crevice corrosion at the modular head-neck junction. It is characterized by elevated serum cobalt levels (often disproportionate to chromium) and ALTR, particularly associated with large head sizes and small/short trunnions.

Question 1431

Topic: 3. Adult Reconstruction (Hip & Knee)

Regarding the kinematics of the native knee and its replication in total knee arthroplasty (TKA), what is the primary biomechanical function of femoral rollback during deep flexion?

. It decreases the patellofemoral compressive force
. It prevents posterior subluxation of the tibia
. It maximizes the moment arm of the extensor mechanism and delays posterior impingement
. It centralizes the patella within the trochlear groove
. It relaxes the collateral ligaments to allow internal rotation

Correct Answer & Explanation

. It decreases the patellofemoral compressive force

Explanation

Femoral rollback (posterior translation of the femoral condyles on the tibia during flexion) clears the posterior aspect of the femur from impinging on the posterior tibia, allowing for greater flexion. It also improves the quadriceps moment arm.

Question 1432

Topic: 3. Adult Reconstruction (Hip & Knee)

A 79-year-old male is scheduled for a total hip arthroplasty. He has a history of severe heterotopic ossification (HO) following a contralateral THA. Which of the following prophylactic regimens is most appropriate to prevent HO in this patient?

. Postoperative continuous passive motion (CPM) for 7 days
. Single-dose perioperative external beam radiation (700-800 cGy)
. High-dose oral calcium supplementation
. Intravenous tranexamic acid
. Prolonged immobilization in an abduction brace

Correct Answer & Explanation

. Postoperative continuous passive motion (CPM) for 7 days

Explanation

Prophylaxis for heterotopic ossification in high-risk patients typically involves either a single fraction of external beam radiation (700-800 cGy) given preoperatively or immediately postoperatively, or an oral NSAID such as Indomethacin for 2-6 weeks.

Question 1433

Topic: 3. Adult Reconstruction (Hip & Knee)

When setting femoral rotation during a primary total knee arthroplasty, the surgeon aligns the epicondylar axis. If the surgeon mistakenly references the posterior condylar axis in a severely valgus knee with lateral femoral condyle hypoplasia without compensating for it, what is the most likely error?

. The femoral component will be excessively externally rotated
. The femoral component will be excessively internally rotated
. The joint line will be significantly elevated
. The extension gap will become asymmetric
. The patella will track too medially

Correct Answer & Explanation

. The femoral component will be excessively externally rotated

Explanation

In a valgus knee, the lateral posterior condyle is often hypoplastic. Using a standard 3 degrees of external rotation off the posterior condylar axis (PCA) without accounting for this hypoplasia will result in excessive internal rotation of the femoral component.

Question 1434

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old woman presents with persistent, disabling knee stiffness 8 weeks after a primary total knee arthroplasty. Her active range of motion is 15 to 65 degrees. Physical therapy has failed to improve her motion. Radiographs show well-positioned components without loosening. What is the most appropriate next step in management?

. Revision total knee arthroplasty
. Arthroscopic lysis of adhesions
. Manipulation under anesthesia
. Botulinum toxin injection to the quadriceps
. Observation and reassurance for another 6 months

Correct Answer & Explanation

. Revision total knee arthroplasty

Explanation

Manipulation under anesthesia (MUA) is most successful when performed within the first 12 weeks after TKA for refractory stiffness. Waiting beyond 12 weeks decreases the success rate and increases the risk of complications such as supracondylar femur fracture.

Question 1435

Topic: Total Knee Arthroplasty (TKA)

A patient presents with a recurrent knee effusion and a feeling of "giving way" when descending stairs 1 year after a posterior-stabilized TKA. Radiographs show well-fixed components. Physical exam reveals increased anteroposterior laxity at 90 degrees of flexion but stability in full extension. What intraoperative error most likely caused this isolated flexion instability?

. Inadequate posterior femoral condyle resection
. Excessive posterior femoral condyle resection
. Excessive distal femoral resection
. Inadequate distal femoral resection
. Placing the tibial component in excessive varus

Correct Answer & Explanation

. Inadequate posterior femoral condyle resection

Explanation

Excessive resection of the posterior femoral condyles abnormally increases the flexion gap without affecting the extension gap. This leads to flexion instability, classically presenting with poor stair descent and recurrent effusions.

Question 1436

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old male complains of a high-pitched, audible squeaking from his hip during walking 3 years after a primary total hip arthroplasty. Radiographs show well-fixed components with a cup abduction angle of 55 degrees. Which combination of bearing surfaces is most associated with this clinical phenomenon?

. Cobalt-chromium on highly cross-linked polyethylene
. Ceramic on highly cross-linked polyethylene
. Ceramic on ceramic
. Oxinium on highly cross-linked polyethylene
. Cobalt-chromium on cobalt-chromium

Correct Answer & Explanation

. Cobalt-chromium on highly cross-linked polyethylene

Explanation

Squeaking is a known complication specific to ceramic-on-ceramic bearings. It is often associated with edge loading due to component malposition, such as excessive acetabular cup abduction or version.

Question 1437

Topic: 3. Adult Reconstruction (Hip & Knee)

When evaluating a painful total knee arthroplasty for potential periprosthetic joint infection, which of the following synovial fluid biomarkers acts by binding to microbial cell membranes, forming pore-like defects, and offers exceptionally high sensitivity and specificity?

. C-reactive protein (CRP)
. Interleukin-6 (IL-6)
. Leukocyte esterase
. Alpha-defensin
. Procalcitonin

Correct Answer & Explanation

. C-reactive protein (CRP)

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils that kills pathogens by disrupting their cell membranes. It is a highly accurate biomarker for diagnosing periprosthetic joint infection, largely unaffected by concurrent antibiotic use.

Question 1438

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female presents with a periprosthetic femur fracture 12 years after a primary THA. Radiographs reveal a fracture around a loose femoral stem with severe comminution and nearly completely deficient proximal bone stock extending to the diaphysis. According to the Vancouver classification, what is the most appropriate surgical treatment?

. Open reduction and internal fixation with a lateral locking plate
. Revision to a standard length fully porous-coated stem
. Revision to a long cemented stem
. Proximal femoral replacement
. Cortical strut allografts and cerclage wiring alone

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locking plate

Explanation

This is a Vancouver B3 fracture, defined by a fracture around a loose stem with severely deficient proximal bone stock. Proximal femoral replacement or a severely augmenting salvage technique is typically required.

Question 1439

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, the surgeon accidentally internally rotates the femoral component 5 degrees relative to the surgical epicondylar axis. What is the most likely biomechanical consequence of this positioning error?

. Lateral patellar tilt and increased risk of patellar subluxation
. Medial patellar tilt and increased risk of patellar subluxation
. Increased flexion space medially
. Decreased flexion space laterally
. Tightness in extension laterally

Correct Answer & Explanation

. Lateral patellar tilt and increased risk of patellar subluxation

Explanation

Internal rotation of the femoral component translates the trochlear groove medially, effectively increasing the Q-angle. This increases the lateral subluxation forces on the patella, leading to lateral tilt and potential dislocation.

Question 1440

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male sustains a supracondylar femur fracture just above a posterior-stabilized total knee arthroplasty. Radiographs confirm the fracture is displaced but the femoral component remains rigidly fixed with no osteolysis. What is the preferred surgical treatment?

. Nonoperative management in a hinged knee brace
. Revision to a distal femoral replacement
. Open reduction and internal fixation with a laterally based locking plate
. Revision to a hinged total knee arthroplasty
. Immediate above-knee amputation

Correct Answer & Explanation

. Nonoperative management in a hinged knee brace

Explanation

This describes a Lewis-Rorabeck Type II fracture (displaced fracture with a well-fixed prosthesis). The gold standard treatment is osteosynthesis, typically with a lateral locking plate that spans the fracture and avoids the component.

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